A basic input/output system (BIOS) is software built into a computing system (known for this reason as firmware) that is the first software run when the computing system is powered on, or “booted.” The BIOS is generally specifically designed for a particular model of computer having particular hardware and chipsets. The BIOS is typically stored on a dedicated non-volatile memory device, where non-volatile refers to the ability to retain stored data when power is removed. BIOS are often stored on read-only memory (ROM), such as an electrically erasable programmable read-only memory (EEPROM), installed on the system motherboard. Some modern computing systems store the BIOS on flash memory, which is a type of EEPROM. Flash memory adds the benefit of being able to load the BIOS to the flash memory without removing the device from the motherboard.
The fundamental purpose of the BIOS is to initialize and test system hardware components and to load other software from other memory, such as a hard drive. Hardware components of concern to the BIOS can include display adapters, audio adapters, communication devices such as network interface cards (NICs) and modems, storage devices, and input devices such as a keyboard, mouse, joystick, hand-held controllers, microphones, and cameras. Some BIOS also provide a layer of abstraction for the hardware components to unify the way applications, the operating system (OS), and other software interact with the hardware. Once initialization and testing of the hardware components are completed, the BIOS typically loads an (OS).
Similar to the BIOS on a computing system, many graphics cards, or “graphics processing subsystems” include a VBIOS. The VBIOS is responsible for initializing and testing hardware components on the graphics processing subsystem and provides a set of functions usable by software programs to access the graphics processing hardware. The VBIOS interfaces the software to the video chipset in the graphics processing subsystem in the same way the system BIOS does for the central processing unit (CPU) in the computing system.